FILE — In this Jan. 27, 2016, file photo, an Aedes aegypti mosquito known to carry the Zika virus, is photographed through a microscope at the Fiocruz institute in Recife, Pernambuco state, Brazil. Zika virus ravages the testes of male mice, sharply reducing sperm counts and fertility, said a study that raises a new specter about its threat to people. The mouse results appear in a paper released Monday, Oct. 31, by the journal Nature.

SALT LAKE CITY — Even as temperatures drop, researchers in Utah are continuing to race toward a treatment for Zika virus, the mosquito-borne illness that has caused birth defects in thousands of children in Latin America and infected hundreds of pregnant women in the U.S.

"This is some of the fastest-paced research I've ever seen," said Justin Julander, a research associate professor at Utah State University's Institute for Antiviral Research.

"Before this large outbreak occurred, there were probably just a handful of papers," he said. "Now there's probably 20, 30 papers being published a week."

Julander and his team are researching how Zika can pass through a pregnant woman's placenta to the fetus, leading to the birth defects that have made Zika so alarming.

Using mice, USU researchers have found a tantalizing hint: The virus appears to replicate particularly quickly in the placenta compared with other parts of the body.

In another study, Julander and his team found that the virus also replicates quickly in testicle tissue and can stay there longer than it stays in the bloodstream. That offers a useful clue as to how the virus is sexually transmitted.

"Once we have a better understanding of that, we can try to apply some of these treatments to see if we can prevent transmission from mother to fetus," Julander said.

Utah State is among several local universities and biotech companies that have joined the fight against Zika.

Researchers at the University of Utah have uncovered how the virus may have passed through the tears and sweat of an elderly patient to his son. Public health officials have called the case a mystery.

University of Utah infectious disease experts are also working with the U.S. Olympic team and their families who returned from the Rio Games in Brazil, where Zika has been rampant.

A Utah resident was confirmed to be infected with Zika within the last week, bringing the total number of infected Utahns to 19, according to the Utah Department of Health.

Researchers have been challenged by how little they understand about Zika, which was once considered a relatively mild illness.

USU molecular virology professor Young-Min Lee spent 15 years working on Japanese encephalitis virus — a very similar pathogen to Zika.

He and his team sequenced the genomes of three different Zika strains — one isolated in Uganda, one from Malaysia and the one that is currently circulating in Latin America — to compare how the virus has changed over time.

They found some "unique differences" that Lee hopes will help unlock the mystery of why the current Zika outbreak has caused such devastating neurological complications.

"There must be a reason why we are seeing these kinds of problems," Lee said. "So we want to understand, genetically, what is the difference."

The next step is to play with the virus by deleting or mutating certain parts of the genome to try to disrupt its critical functions.

Lee is doing this using a technology he originally developed for Japanese encephalitis that converts the virus’ RNA into something called complementary DNA. He then introduces mutations into the DNA to study which genes are critical for the virus to replicate or infect people.

Several Utah biotech companies are also working on more accurate and cheaper diagnostic tests.

Co-Diagnostics, a small biotech in Sandy, developed a Zika test several times cheaper than the one offered by the Centers for Disease Control and Prevention by applying sophisticated mathematics to speed up the process.

The company started offering the $12 test in labs in the South American country Guyana last week.

"It's in our mission statement to take affordable testing to the people in the nations that need them the most," said Co-Diagnostics international sales manager Seth Egan.

Egan said the company is hoping to obtain World Health Organization and Federal Drug Administration approval to begin distributing the test in the U.S. and abroad.

Salt Lake-based ARUP Laboratories is also developing its own diagnostic Zika test, which will be available in a few weeks, according to infectious disease rapid testing medical director Marc Couturier.

The lab currently offers commercial Zika testing and has tested about 50 people, he said.

The state of Zika research, Couturier said, is a "full-frontal attack," from the efforts of epidemiologists on the ground in South America and Florida, to the doctors in the clinics reporting what they're seeing in patients and babies, to the scientists in the labs working on a cure.

"Pretty much everyone's all hands on deck with it," he said. "It's pretty amazing to see."